To add an icon to the users cpanel, you would have to alter the theme files ( /usr/local/cpanel/base/frontend/themename ) that the user is using.

You will need root access to the server, resellers can contact their host to see if they will obtain the necessary files for you. However they may very well say `no`.

Also during cPanel updates some themes ( like the `x` theme ) get overwritten. To workaround that, copy & rename the theme ( ie `myx` ) Upload the new theme to the server and change each user to use that theme that you want to have the icon available to the user.

Also using some themes ( 3rd party themes, developed outside of cPanel ) allow easy customization of themes.